Field of the Invention
The present invention relates to hydraulic mounts. More particularly, the present invention relates to a hydraulic mount, which allows the vertical behavior of a membrane and induces a rotation, thus further improving noise, vibration, harshness (NVH) performance, in addition to further increasing durability.
Description of Related Art
In order to dampen the vibration of an engine, the engine of a vehicle is installed in an engine room of a vehicle body via an engine mount. As the engine mount, a rubber mount using an elastic force of a material and a hydraulic mount filled with liquid to dampen vibration using viscosity resistance to a liquid flow are widely used.
Above all, the hydraulic mount is configured to dampen vibration in both a high frequency domain and a low frequency domain, so that it is widely used in various kinds of vehicles.
FIG. 1A illustrates the configuration of a conventional hydraulic mount. Referring to the drawing, the hydraulic mount is configured such that an internal space between an insulator 300 and a diaphragm 500 is filled with a predetermined amount of hydraulic liquid, and a nozzle plate 400 is mounted between the insulator 300 and the diaphragm 500 to partition the internal space into an upper liquid chamber and a lower liquid chamber.
Further, the nozzle plate 400 is configured such that an upper plate 400a is coupled to an upper surface thereof, with an annular path being formed along an edge of the nozzle plate 400 and causing the upper liquid chamber and the lower liquid chamber to communicate with each other to thereby allow hydraulic liquid to flow. Moreover, in order to improve dynamic characteristics, a membrane 100 is mounted adjacent to a location where a center hole of the upper plate 400a is coupled with a center hold of the nozzle plate 400.
The insulator 300 is coupled with a core 200, and a load of the engine is transmitted to the core 200. Thus, the insulator 300 made of a material such as synthetic rubber or synthetic resin to have elasticity repeats elastic compression or restoration according to a change in load and vibration of the engine. The hydraulic liquid filled therein flows through the path to the upper liquid chamber and the lower liquid chamber.
Such a flow of the hydraulic liquid causes the membrane 100 to be vibrated up and down as shown in FIG. 1B. The vibration of the high frequency domain is dampened by the vibration of the membrane 100, while the vibration of the low frequency domain is dampened by the flow of the hydraulic liquid through the path.
Meanwhile, the membrane 100 is classified into a movable type membrane (a plurality of holes is perforated in the membrane) and a semi-fixed type membrane (a membrane is formed in a disc shape and some of hydraulic liquid flows along an edge of the membrane in a mounting recess) depending on a mounting method. The semi-fixed type membrane making it easy to secure a loss factor is more widely used.
However, the hydraulic mount configured such that the membrane 100 is mounted in the semi-fixed manner has two drawbacks in terms of degradation and durability.
First, the membrane 100 made of rubber is expanded by the degradation, and produces sludge to block a gap, which is a passage where the hydraulic liquid flows and is shown by bold lines on left and right sides of FIG. 1B, around the membrane 100, so that dynamic characteristics may be significantly increased and thereby NVH performance may be deteriorated.
Further, in order to fix the membrane 100 (for the purpose of securing the loss factor), a steel plate is provided in the membrane 100. However, the steel plate is problematic in that it strikes the upper plate 400a and the nozzle plate 400 above and below the mounting recess while the membrane 100 is vibrated, thus generating a rattle noise.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.